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Date:   Fri, 24 Mar 2023 12:17:30 +0200
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To:     David Gow <davidgow@google.com>
Cc:     Maxime Ripard <maxime@cerno.tech>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Brendan Higgins <brendan.higgins@linux.dev>,
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        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        kunit-dev@googlegroups.com, Stephen Boyd <sboyd@kernel.org>,
        Jonathan Cameron <jic23@kernel.org>, linux-iio@vger.kernel.org
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From:   Matti Vaittinen <mazziesaccount@gmail.com>
Subject: Re: [PATCH v5 1/8] drivers: kunit: Generic helpers for test device
 creation
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On 3/24/23 12:05, Matti Vaittinen wrote:
> On 3/24/23 11:52, David Gow wrote:
>> On Fri, 24 Mar 2023 at 14:51, Matti Vaittinen 
>> <mazziesaccount@gmail.com> wrote:
>>>
>>> On 3/24/23 08:34, David Gow wrote:
>>>> On Fri, 24 Mar 2023 at 14:11, Matti Vaittinen 
>>>> <mazziesaccount@gmail.com> wrote:
> 
>>>> I think that sounds like a good strategy for now, and we can work on a
>>>> set of 'generic helpers' which have an associated bus and struct
>>>> kunit_device in the meantime. If we can continue to use
>>>> root_device_register until those are ready, that'd be very convenient.
>>>
>>> Would it be a tiny bit more acceptable if we did add a very simple:
>>>
>>> #define kunit_root_device_register(name) root_device_register(name)
>>> #define kunit_root_device_unregister(dev) root_device_unregister(dev)
>>>
>>> to include/kunit/device.h (or somesuch)
>>>
>>> This should help us later to at least spot the places where
>>> root_device_[un]register() is abused and (potentially mass-)covert them
>>> to use the proper helpers when they're available.
>>>
>>
>> Great idea.
>>
>> The code I've been playing with has the following in 
>> include/kunit/device.h:
>>
>> /* Register a new device against a KUnit test. */
>> struct device *kunit_device_register(struct kunit *test, const char 
>> *name);
>> /* Unregister a device created by kunit_device_register() early (i.e.,
>> before test cleanup). */
>> void kunit_device_unregister(struct kunit *test, struct device *dev);
>>
>> If we used the same names, and just forwarded them to
>> root_device_register() and root_device_unregister() for now
>> (discarding the struct kunit pointer), then I expect we could just
>> swap out the implementation to gain the extra functionality.

There's one thing though. If the goal is to do a direct replacement and 
if automatic device deletion upon test completion / test abort is 
planned - then it should be there also for these initial wrappers.

If these wrappers don't yet include the automatic device clean-up - then 
it probably makes more sense to just do the kunit_root_device_* defines 
because the tests are likely to need removing the explicit device 
clean-ups when proper APIs are finished.

Yours,
	-- Matti

-- 
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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